Coaxial line switch



1960 c. F. SCHUNEMANN EIAL 2,966,637

COAXIAL LINE SWITCH 2 Sheets-Sheet 1 Filed Jan. 31, 1956 1 4 as 15 I EZWZIFE CARL F SCHUNEMANN Gauges E. JAcQuEs I6 45 I 11 Z5 Dec. 27, 1960 c. F. SCHUNEMANN ETAL 7 COAXIAL LINE SWITCH Filed Jan. 31, 1956 2 Sheets-Sheet 2 CARL F SCHUNEMANN o M J E E G R O E\ h United States Patent COAXIAL LINE SWITCH Carl F. Schunemann, Euclid, and George E. Jacques, Independence, Ohio, assignors to Thompson Ramo Wooldridge Inc., a corporation of Ohio Filed Jan. 31, 1956, Ser. No. 562,382

7 Claims. (Cl. 333-7) This invention relates to a coaxial line switch in which a wall conductive material is joined at the edges of openings therein around the terminal ends of coaxial line outer conductors with a switch blade being provided for connecting the terminal end of the inner conductor of one of the lines selectively to the inner conductors of the other lines. A shield is preferably secured to the wall to prevent radiation from the switch and to prevent external fields from affecting the operation of the switch.

In a switch of this type heretofore proposed, four parallel coaxial lines are disposed with lines from the axis of the first line to the axes of the second and third lines defining a 60 angle and with lines from the axis of the first line to the axes of the third and fourth lines also defining a 60 angle, the axes of the second, third and fourth lines being spaced equal distances from the axis of the first line. With this arrangement, the lines are located as closely together as is possible. A shield is provided of generally rectangular shape having a first pair of side walls parallel to each other and to a line through the axes of the second and fourth lines and a second pair of side walls parallel to each other and to a line through the axes of the first and third lines. With a switch of this construction, very satisfactory operation can be obtained with a voltage standing wave ratio very close to unity in a certain range or ranges of high frequencies. However, at frequencies outside such ranges, very high standing wave ratios are obtained. It has been found that such high voltage standing wave ratios are caused not by the construction of the basic switch atrangement, but by resonant cavity effects produced by the shield.

In general, the resonant frequency of the shield is decreased as its Size is increased. It would therefore appear desirable to make the shield as small as possible so that the lowest resonant frequency would be as high as possible. However, if it is attempted to make the shield very small, it will have internal surface portions disposed so close to the base wall which interconnects the coaxial line outer conductors that it will affect the operation of the switch structure and produce other resonants effects. It is therefore an object of this invention to provide a shield in which resonance effects are mimized but in which the internal surfaces which face the base wall are spaced a substantial distance therefrom.

Another object of this invention is to provide a coaxial switch of the type described above in which the shield is not only efficient in operation but is readily and economically manufacturable and easily attached to the switch.

According to this invention, a shield is provided in which the internalsurfaces which face the base wall are spaced a substantial distance therefrom and in which the side walls of the shield are formed in such a manner as to prevent resonant cavity effects.

According to a specific feature of the invention, the shield has a plurality of side walls each extending generally parallel to a line through the axes of an adjacent pair of the coaxial lines. Thus, in a switch constructed as described above, the shield may have one wall portion generally parallel to a line through the axes of the first and second lines; a second wall portion generally parallel to a line through the axes of the secondand third lines; a third wall portion generally parallel to a line through the axes of the third and fourth lines; and a fourth wall portion generally parallel to a line through the axes of the first and fourth lines. With this arrangement the resonant frequency of the shield is increased substantially and at the same time, the switch is made more compact.

In one embodiment of the invention the side wall portions of the shield are at right angles to the base wall, while in another embodiment of the invention, the side wall portions of the shield converge angularly inwardly from the base wall so that the shield is of generally pyrimidal or frusto-pyrimidal shape. The first embodiment is preferred from the standpoint of economy of manufacture while somewhat better operational characteristics are obtained with the second embodiment rela tive to the overall size of the shield.

Another feature of the invention is in the provision of baffle plates extending inwardly from the internal surfaces of the shield, preferably from the side walls. With such plates, the resonance effects are minimized without decreasing the spacing between the base wall and the internal surfaces of the shield in facing relation thereto.

This invention contemplates other objects, features and advantages which will become more fully apparent from the following detailed description taken in conjunction with the accompanying drawings which illustrate preferred embodiments and in which:

Figure l is a perspective view of one preferred embodiment of coaxial line switch constructed according to the principles of this invention;

Figure 2 is a sectional view taken substantially along line II--Il of Figure 1;

Figure 3 is a sectional view taken substantially along line III-III of Figure 2;

Figure 4 is a top plan view of another preferred embodiment of coaxial line switch constructed according to the principles of this invention; and

Figure 5 is a side elevational view of the switch of Figure 4.

Reference numeral 10 generally designates a coaxial line switch constructed according to the principles of this invention which is particularly designed to selectively connect one coaxial line 11 to any one of three other coaxial lines 12, 13 and 14. The switch 10 is operated by rotation of an operating handle 15 on a housing 16 of conductive material which includes a shield 17 mounted on a wall 18 forming the bottom wall of the housing, the shield having a top wall 19 spaced from the bottom or base wall 18. The bottom wall 18 is covered by a sheet 20 of insulating material and has four circular openings therein and is joined at the edges of such openings around the terminal ends of the outer conductors 21, 22, 23 and 24 of the lines 11, 12, 13 and 14 respectively. The outer conductors 2124 may, for example, be soldered to the bottom wall 18 around the openings therein and it will be noted that the upper surface of the bottom wall forms an electrical continuation of the inner surfaces of the coaxial line outer conductors.

The coaxial line 11 has an inner conductor 25 which is selectively connected to inner conductors 26, 27 and 28 of the coaxial lines 12, 13 and 14, respectively, by means of a switch blade 29 which is rotated about the axis of the line 11 and has one end portion 30 engaged with the terminal end of the inner conductor 25 with the other end portion 31 thereof being selectively engaged with the terminal ends of the inner conductors 26, 27

and 28. In the illustrated position of the blade 29, the end portion 31 thereof is engaged with the terminal end of the inner conductor 27 and with rotation through 60 in a clockwise direction as viewed in Figure 2, the end portion 31 will be engaged with the terminal end of the conductor 28 or with rotation through 60 in a counterclockwise direction, the terminal end portion 31 will be engaged with the end of the conductor 26.

For effecting rotation of the switch blade 29, the end portion 30 thereof is connected through a coupling 32 to the lower end of a vertical shaft 33 which has its upper end connected to the operating handle 15.

To obtain the best possible electrical contact between the switch blade 29 and the terminal ends of the coaxial line inner conductors 25-28, the switch blade is of magnetic material and magnets 34, 35, 36 and 37 are mounted on the terminal ends of the inner conductors 25, 26, 27 and 28 respectively.

The magnet 34 is mounted in a sleeve 38 the opening of which is enlarged at its upper end to provide a gap of non-magnetic material, either air or solder 39 as desired. The sleeve 38 extends through an opening in the insulating sheet 28 and has an annular flange portion 48 overlying the sheet 20 about such opening. The lower end portion of the sleeve 38 is mounted within a sleeve 41 which is mounted within the inner conductor 25 of the line 11. The magnets 35, 36 and 37 are similarly mounted within sleeves 42, 43 and 44 carried by the inner conductors 26, 27 and 28. The switch blade 29 and the magnets 3437 have highly conductive wear-free material brazed to them at the contact points.

According to this invention, the shield 17 has a first side wall portion 45 extending generally parallel to the axes of the lines 11 and 12, a second side wall portion 46 extending generally parallel to a line through the axes of the lines 12 and 13, a third wall portion 47 extending generally parallel to a line through the axes of the lines 13 and 14, and a fourth wall portion 48 extending generally parallel to a line through the axes of the lines 11 and 14. Each of the side wall portions 45-48 is spaced outwardly from the outer conductors of the adjacent coaxial lines.

The side wall portions 45 and 46 may converge to a line at which they are interconnected. Preferably, however, they are connected by a side wall portion 49 spaced outwardly from the outer conductor 22 of the line 12 a distance approximately equal to the spacing of the side wall portions 45 and 46 therefrom. Side wall portions 50, '51 and 52 similarly connect the side wall portions 46, 47, the side wall portions 47, 48 and the side wall portions 45 and 48. With this construction, the resonant frequency of the shield 17 is raised substantially without decreasing the spacing between the walls 18 and 19.

v For example, in a switch of this construction in which the outer diameter of the outer coaxial line conductors is 3 /8 inches with a spacing of inch between such outer conductors, and in which the length (distance between said wall portions 49 and 51) is 12 inches with a width of 9 inches and a height of 5 inches, the lowest frequency of resonants was found to be about 960 megacycles while a rectangular shield having the same length, width and height was resonant at 860 megacycles.

According to a specific feature of the invention, a plurality of bafile plates 5364 extend inwardly from the side walls of the shield, the baflie plates 5364 being preferably formed integrally with the side walls. With a switch having dimensions such as described in the next preceding paragraph and with the baffie plates 5364 positioned as illustrated in Figure 2, it has been found that the lowest frequency of resonants of the shield is 1060 megacycles, compared to 960 megacycles without the battle plates. The optimum length and spacing of the baffle plates will, of course, vary but in general there should be at least four and preferably a greater number spaced around the inside of the shield, and each plate should extend inwardly a distance at least of the spacing therebetween. It will be appreciated, of course, that other practical considerations, such as the ease and cost of formation of the plates, enter into the choice of the number and the size of the plates. It should be noted that the baflle plates may be used to greatest advantage by positioning them vertically on the side walls as is illustrated, but improved results may also be achieved by disposing bafile plates horizontally on the side walls and by disposing the plates on the undersurface of the top wall.

Referring now to Figures 4 and 5, reference numeral '65 generally designates another preferred form of switch constructed according to the principles of this invention. The switch 65 uses a switch blade 66 (shown only in dotted lines in Figure 4) to selectively connect the terminal end of the inner conductor of one line 67 to the terminal ends of the inner conductors of lines 68, 62 and 70. The switching structure is preferably identical to that illustrated in Figures 2 and 3 and described in detail above.

The switch 65 comprises a housing which includes a shield 71 secured on a bottom wall 72, the bottom wall 72 having openings therein and being joined at the edges of such openings about the terminal ends of the outer conductors of the coaxial lines 67-70.

The shield 71 has a side wall portion 73 disposed generally parallel to a line through the axes of the lines 67 and 68, a side wall portion 74 disposed generally parallel to a line through the axes of the coaxial lines 68 and 69, a side wall portion 75 disposed generally parallel to a line through the axes of the coaxial lines 69 and 70, and a side wall portion 76 disposed generally parallel to a line through the axes of the coaxial lines 67 and 70.

Instead of extending vertically (normal to the base wall 72), the side wall portions 73-76 converge angularly inwardly either to a point or preferably to a top wall portion 77 having an area which is much less than the area of the base wall 72.

The side wall portions 73 and 74 may converge to a line at which they are joined but preferably are connected by a side wall portion 78 of generally triangular shape which is spaced from the outer conductor of the line 68 at the base wall 72 a distance approximately equal to the spacing of the wall portions 73 and 74 from the outer conductor of the line 68 at the base wall 72. Similar side wall portions 79, 80 and 81 respectively connect the side wall portions 74 and 75, the side wall portions 75 and 76 and the side wall portions 73 and 76.

In a switch of this construction in which the outer diameter of the coaxial line outer conductors is 3% inches with a spacing of inch between such outer conductors, and in which the length (distance between the lower ends of the wall portions 78 and 80) was 12 inches with a width of 9 inches and a height of 5 inches, the lowest frequency of resonance was found to be at about 1150 megacycles as compared to 860 megacycles for a similar switch using a rectangular shield of the same length, width and height.

Baflie plates may be used to further improve the characteristics of the shield 71, if desired.

For operating the switch 65, an inverted L-shaped bracket 82 is provided having one leg 83 secured against the top wall 77 with the other leg 84 secured at its lower end to the side wall portion 81, and a shaft 85 is connected at its lower end to the switch blade 66 and extends upwardly through the side wall portion 81 and through the leg 83, with an operating handle 86 secured to the upper end of the shaft 85.

It will be understood that modifications and variations may be effected without departing from the spirit and scope of the novel concepts of this invention.

We claim as our invention:

1. in a switch for selectively connecting one coaxial line to a plurality of other coaxial lines, said lines being disposed in generally parallel relation with each having inner and outer conductors, a base wall of conductive material having openings therein and being joined at the edges of said openings around the terminal ends of the outer conductors, a selectively movable switch blade for selectively interconnecting the inner conductors of said one coaxial line to the inner conductors of the other coaxial lines and disposed in spaced relation to one side of said wall to define a ground plane type transmission line section, and a stationary shield of conductive material secured to said wall on said one side thereof for preventing radiation from said switch without affecting the transmission of energy from one coaxial line to another to said switch blade, said shield having a plurality of side wall portions each disposed generally parallel to a line through the axes of an adjacent pair of the coaxial lines.

2. In a switch for selectively connecting the first coaxial line to second and third coaxial lines each having inner and outer conductors and being disposed in generally parallel relation, a wall of conductive material having openings therein and being joined at the edges of said openings around the terminal ends of said outer conductors, a selectively movable switch blade for selectively interconnecting the inner conductor of said first line to the inner conductors of said second and third lines and disposed in spaced relation to one side of said wall to define a ground plane type transmission line section, and a stationary shield of conductive material secured to said wall on said one side thereof for preventing radiation from said switch without affecting the transmission of energy from one coaxial line to another, said shield having a side wall including a first side wall portion generally parallel to a line connecting the axes of said first and second coaxial lines and a second side wall portion generally parallel to a line connecting the axes of said first and third coaxial lines.

'3. In a switch for selectively connecting one coaxial line to a plurality of other coaxial lines, said lines being disposed in generally parallel relation with each having inner and outer conductors, a base wall of conductive material having openings therein and being joined at the edges of said openings around the terminal ends of the outer conductors, a selectively movable switch blade for selectively interconnecting the inner conductors of said one coaxial line to the inner conductors of the other coaxial lines and disposed in spaced relation to one side of said wall to define a ground plane type transmission line section, and a stationary shield of conductive material secured to said wall on said one side thereof for preventing radiation from said switch without affecting the transmission of energy from one coaxial line to another to said switch blade, said shield having a plurality of side wall portions each disposed generally parallel to a line through the axes of an adjacent pair of the coaxial lines, said side wall portions being disposed generally normal to said base wall.

4. In a switch for selectively connecting one coaxial line to a plurality of other coaxial lines, said lines being disposed in generally parallel relation with each having inner and outer conductors, a base wall of conductive material having openings therein and being joined at the edges of said openings around the terminal ends of the outer conductors, a selectively movable switch blade for selectively interconnecting the inner conductors of said one coaxial line to the inner conductors of the other coaxial lines and disposed in spaced relation to one side of said wall to define a ground plane type transmission line section, and a stationary shield of conductive material secured to said wall on said one side thereof for preventing radiation from said switch without aflfecting the transmission of energy from one coaxial line to another to said switch blade, said shield having a plurality of side wall portions each disposed generally parallel to a line through the axes of an adjacent pair of the Cir coaxial lines, and a plurality of baffle plates extending inwardly from the internal surface of said shield.

5. In a switch for selectively connecting one coaxial line to a plurality of other coaxial lines, said lines being disposed in generally parallel relation with each having inner and outer conductors, a base wall of conductive material having openings therein and being joined at the edges of said openings around the terminal ends or" the outer conductors, a selectively movable switch blade for selectively interconnecting the inner conductors of said one coaxial line to the inner conductors of the other coaxial lines and disposed in spaced relation to one side of said wall to define a ground plane type transmission line section, and a stationary shield of conductive material secured to said Wall on said one side thereof for preventing radiation from said switch Without affecting the transmission of energy from one coaxial line to another to said switch blade, said shield having a plurality of side wall portions each disposed generally parallel to a line through the axes of an adjacent pair of the coaxial lines, and a plurality of baffie plates extending inwardly from the internal surface of said shield and disposed in planes generally normal to said base wall.

6. In a switch for selectively connecting one coaxial line to a plurality of other coaxial lines, said lines being disposed in generally parallel relation with each having inner and outer conductors, a base wall of conductive material having openings therein and being joined at the edges of said openings around the terminal ends of the outer conductors, a selectively movable switch blade for selectively interconnecting the inner conductors of said one coaxial line to the inner conductors of the other coaxial lines and disposed in spaced relation to one side of said wall to define a ground plane type transmission line section, and a stationary shield of conductive material secured to said wall on said one side thereof for preventing radiation from said switch without affecting the transmission of energy from one coaxial line to another to said switch blade, said shield having a plurality of side wall portions each disposed generally parallel to a line through the axes of an adjacent pair of the coaxial lines, each of said side wall portions being converged angularly inwardly.

7. In a switch for selectively connecting the first coaxial line to second and third coaxial lines each having inner and outer conductors and being disposed in generally parallel relation, a wall of conductive material having openings therein and being joined at the edges of said openings around the terminal ends of said outer conductors, a selectively movable switch blade for selectively interconnecting the inner conductor of said first line to the inner conductors of said second and third lines and disposed in spaced relation to one side of said wall to define a ground plane type transmission line section, and a stationary shield of conductive material secured to said wall on said one side thereof for preventing radiation from said switch without affecting the transmission of energy from one coaxial line to another, said shield having a side wall including a first side wall portion generally parallel to a line connecting the axes of said first and second coaxial lines and a second side wall portion generally parallel to a line connecting the axes of said first and third coaxial lines, said side wall portions being converged angularly inwardly.

References Cited in the file of this patent UNITED STATES PATENTS 2,306,282 Samuel Dec. 22, 1942 2,445,793 Marchand July 27, 1948 2,498,907 Atwood et al. Feb. 28, 1950 2,593,155 Kinzer Apr. 15, 1952 2,694,795 Pureka Nov. 16, 1954 2,697,767 Charles Dec. 21, 1954 2,759,152 Charles Aug. 14, 1956 2,784,379 Schunemann Mar. 4, 1957 

